Magnetic image plate



Feb. 11, 1964 E. J. suP-:RNowcz & 30

MAGNETIC IMAGE PLATE Filed April 24, 1957 7 Sheets-Sheet 1 Ja F/GJ 7///////////7\)///////////////WWW/#JA NVENTO?. EDWARD J. SUPERNOW/CZ 4 7'7- o r N Feb. 11, 1964 E. J. SUPERNOWICZ MAGNETIC IMAGE PLATE 7 Sheets-Sheet 2 Filed April 24, 1957 Feb. 1964 E. J. SUPERNOWICZ MAGNETIC IMAGE PLATE 7 Sheets-Sheet 3 Filed April 24, 1957 MAGNETIC IMAGE PLATE 7 Sheets-Sheet 4 Filed April 24, 1957 MNG Feb. 11, 1964 E. J. SUPERNOWICZ MAGNETIC IMAGE PLATE 7 Sheets-Shee'r. 5

Filed April 24, 1957 Feb. ll, 1964 E. J. SUPERNOWICZ MAGNETIC IMAGE PLATE 7 Sheets-Sheet 6 Filed April 24, 1957 g 202 424 ili I I I I I I I I I I I I ll I I I LLLLLLLLLLLLLLL Feb. 11, 1964 E. J. SUPERNOWICZ &

MAGNETIC IMAGE PLATE Filed April 24, 1957 7 Sheets-Sheet 7 United States Patent O 3,120,806 MAGNETIC IMAGE PLATE Edward .l. Supe'nowicz, Santa Clara, Calif., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Apr. 24, 1957, Sei'. No. 654355 4 Claims. (CI. NFL-426) This invention relates to printing and more specifically to a method of magnetically preparing a magnetic image plate for printirg electrical circuits or conventional copy.

In the printed circuit art, the usual method of preparing a printed circuit includes preparing a printing plate for effecting a representation of the conductors of the circuit; making an imprint by the aid of the printing plate upon a surface, differentiating on that surface the areas which are required to be conductive from the areas which are required to be non-conductive; and from the imprint, producing a conductor by subjecting the priuted surface to treatment which operates diiferently on the areas of the surface thus differentiated, such as by etching or by deposition of conductive particles. According to the invention, a magnetic image of' the printed circuit is formed in a magnetically retentive plate. The plate is placed beneath a sheet or base for the printed circuit and magnetic particles are distributed on the sheet, aligning themselves in accordance with the image. In this manner the image plate differentiates upon the sheet or base between areas to be treated and areas not to be treated. An object of this invention, therefore, is the provision of a novel method of prepan'ng a magnetic image plate.

In making the diflerentiating imprint with the printing plate of the prior art, as explained above, it is not unusual to find a certain amount of smudged or darkened areas upon the background, i.e. backgrounding' as that term is understood in the printing art. It is, therefore, another object of this invention to provide a novel image plate which eliminates bachgroundingf? Whenever the imprint is not to be made directly upon the permanent base material upon which the printed circuit will be formed, it is usual for an imprint to be made i upon a temporary base material followed by a contact transfer process. It is another object of this invention, therefore, to provide an improved method of preparing printed circuits which eliminates this process.

It is another object of this invention to provide a novel method of printing magnetically wherein the face of the printing plate is protected against scarring by foreign matter deposited thereon.

It is still another object to provide a method of magnetic printing wherein the definition of the printed copy is improved.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose, by Way of example, the piinciple of the invention and the best mode which has been contemplated of applying that principle.

In the drawings:

FIG. 1 is a perspective View of one type of master copy of a circuit representation.

FIG. la is a sectional view of FIG. 1 taken along line la-la after magnetic particles have been sprinkled upon the tacky ink of the master.

FIG. lb is a sectional View similar to FIG. la after resin-coated particles have been fused upon the ink 101 of the master.

FIG. 2 is a perspective View of another type of master prepared with magnetic ink.

FIG. Za is a sectional View of FIG. 2 taken along line 2a-2a.

FIG. 3 is a perspective View of an engraved type of master.

&120306 Patented Feb. 11, 1964 FIG. 3a is a sectional View of FIG. 3 taken along line 'Sa-Ea showing engraving upon a metal sheet by impact printing thereon.

FIGS. 3b and 3c are sectional Views similar to FIG. 3a showing a partial and total etching respectively, of the master, wherein a sheet of supporting material has been provided beneath the master.

FIG. 4 is a perspective View of a master prepared by gluing a wire upon a lamina or sheet.

FIG. 4a is a sectional view of FIG. 4 taken along line 4a-4a.

FIG. 5 is an-expanded perspective View showing the Creation upon an image plate of a magnetic image (in invisible Outline) of the pattern on the master.

FIG. 6 is also an expanded perspective view showing magnetic alignment of particles in accordance with the image in the image plate.

FIG. 7 is an expanded perspective view showing an alternative method of creating upon the image plate a magnetic image of the pattern on the master.

FIG. 8 is also an expanded perspective view showing magnetic alignment of particles in accordance with the image plate prepared by the method of FIG. 7.

FIG. 9 diagrammatically represents markng of a master.

FIG. 10 shows the positioning of an image plate against a master and their passage together under a magnet.

FIG. 11 shows an image plate with a magnetic image of a master thereon (shown in invisible Outline).

FIG. 12 shows the passage of a circuit base and an image plate together under a hopper depositing magnetc particles.

FlG. 13 shows the passage of a circuit base and an image plate under an air jet as it removes excess particles from the circuit base.

FIG. 14 is a sectional view of a circuit base taken along line 14-14 of FIG. 14a, showing 'the condition of aligned particles thereon prior to their entry into the oven of FIG. 15.

FIG. 14a is a perspective view of the circuit base in FIG. 14.

FIG. 15 shows the fusing of the particles as they are conveyed through an oven.

FIGS. 16 and 16a are a diagrammatic representation in perspective, shown also in section along line 16-16, %f solder dipping of the fused circuit upon the circuit ase.

Fl 17 is a perspective View in partial section of the final "r'hi ted circuit prepared by the process shown in FIGS. 9 through 17.

FIGS. 18 through 22 are similar to FIGS. 9 through 13 and represent the initial steps of preparing printed circuits by an etching method.

FIG. 23 is a perspective View showing heat fusion of protective magnetic particles upon a circuit base by means of a heat source shown as an infrared light.

FIGS. 24 and 24a show the circuit base in perspective and cross-section prior to its entry into the etching bath of FIG. 25.

FIG. 25 is a perspective View of an etching bath shown schematically.

FIG. 26 is a cross-section perspective View of a circuit base taken along line 26-26 of FIG. 25 showing the condition of the circuit base as it leaves the etching bath.

FIG. 27 is a perspective schematic representation of the immersion of the base in a solvent of its protective coating.

FIG. 28 is a perspective view of the finalprinted circuit product showing a solid, conductive circuit upon a circuit base.

FIG. 29 is a greatly enlarged cross-sectional view of a c onductive"magnetic particle 'showing its c'onstituent granules.

FIG. 30 is a greatly enlarged cross-sectional View of granules.

FIG. 3'1 is a greatly enlarged cross-sectional view of a pigmented magnetic particles showing its constituent granules.

I a protective magnetic particle showing its constituent y V FIG. 32 is a perspective view of a printer with partial I sections taken therein for clarity.

FIG. 33 is a sectioned portion of a character drum i 203 showing one Construction there'of.

FIG. 34 shows an alternative Construction of the character drum203.

FIG. 35 is a sectional view of the printer of FIG. 32 taken along line 35-35 of FIG. 32.

FIG. 36 is a perspective view of a duplicator embodying the invention. l

This invention relates to a novel method for producing 4, printed circuits by the aid of forming a magnetc image of 'a circuit representation in a highly retentive magnetc material to be used as an image plate; placing the image V plate thus prepared against a sheet of material, such as 'phenolic, mica, ceramic or porcelain, etc., upon which` the printed circuit willtbe formed; aligning magnetic particles thereon in accordance with the circuit representation; and treating the aligned particles and associatedsheet so as to create circuit conductors in the configuration of` the circuit representation. The image plate itself is com-- prised of any highly retentive magnetic material, such as:

cobalt-nickel. If a magnet of the type which produces vertical lines of flux (herein called a Vertical magnet) is used forpreparing the image plate, the retentive magnetic; material preferably should be plated or coated upon a'. hacking plate of magnetic material of low retentivity to:

aford a concentrated flux through the highly retentive inagnetic material.

referred to as a horizontal magnet) is 'so used.

Since small magnetic particles are not *substantially attracted by a homogeneous magnetic field'when present therein, n'order to magnetically attract and thereby align geneo'us field and then producing the non-homogeneous lines therein." To produce this homogeneousfield on the i( imageplate, it is only necessary to pass the image plate" under'a magnet. This initial step is unnecessary if a magnet of the type producing horizontal lines of fiux is used as the image-creating magnet. magnetic particles, changes in the fiux path reluctance, the

shielding eifect of a conductve material, etc. will produce A' hacking plate is not necessary; where a magnet producing horizontal lines of fiux (heren It has been found that 104 or magnetic carbon paper. Referring to FIGS. 3 and 3a, the printing recorded upon lamina 102 has been engraved therein by impact printing as at 106. As shown in FIGS; 3?) -and 3c, the engraving upon a laminamay be-by a' selective partial or total etching away a s at 107 and 103, respectively. In this case, a non-magnetic supporting material 109 is required to prevent the Centers of the letters from falling out or -to provide added strength to lamina 102. Finally, referring to FIGS. 4 and 4a, a wire 110 of magnetic material of low retentivity (a mu of approximately 30.0r above yields best results) may be gluedtor attached to lamina 102 to form a ,pattern 111. The lamina 102 in FIGS. 1,- 2 and 4 is ofany suitable non-magnetic material, preferably a non-conductor In FIG. 3, lamina 102 maybe of any .suitable magnetic material of low retentivity' having high permeability.

The process of preparing the image plate,.as explained in detail hereinafter, can be summarized as follows:

, (1) A uniform magnetic field is created in a lamina of highlyretentive magnetic material (i.e. an image plate) by subjecting it to unidirectional magnetic flux;

(2) A master, marked as described above with reference to FIGS. 1 through;4, `is placed upon the image plate; and

(3) The master and image plate are pressed together and subjected to the field of a magnet, the master occupying a position between the magnet and-the image plate.

Referring to FIG. ,5, a master 115, produced as described above, hearing representation 116 of the crcuit is positioned upon an image plate 112. Plate 112 is comprised of a 'layer 113 of highly retentive magnetic material, such as cobalt-nickel, and abackng plate 114 of highly permeabIe-magnetic material having low retentivity t characterstics.

^ shown) is used in the process, except as it may be needed diverge'nt lines'of flux in the initially homogeneous field of the image plate. To effect this change, a master copy of the circuit is provided as described hereinafter.

The master is a lamina with a representation of a cirv tcuit marked thereon or therein. It is marked in a manner such that when it is subjected to the field of a magnet, to-

gether With the image plate, it Will selectively producenon-homogeneous lines of flux in the aforementioned homogeneous magnetc field of the image plate. Marking the master to accomplish this result may be done in ,any of several ways; however, it has been found that best results are obtained When the master occupies a position .between the magnet and the highly retentive magnetc to provide hysical support for layer 113. V It is to be noted that by applying master 115 so that the printed material is in contact :with the highly retentive magnetc surface of plate 112, a more effective transfer is produced.

' Th'eplate 112 and master 115 are subjected together to the field of anagnet 117, the master occupying a position I between magnet 117 and plate 112., As shown in FIG. 5,

this is done by passing them under a horizontal magnet 117. .By thus passing the plate 112 and master 115 under the magnet, a latent magnetic image 118 is formed in plate 112, as explained above. The image thus formed is of excellent definiton due to the proximity of representation 116 and plate 112 as they pass through the field i of the magnet.

As 'shown in FIG. 6, withtheimage 118 now formed in plate 112, master 115 is removed and asheet 120 for the printed circuit is placed upon plate 112. Sheet 120 and plate 1 12 are passed .under a hopper 122 and an air jet 123. Special magnetic `particles 121, as described below, are spread from hopper 122 upon sheet 120. Subsequently, air jet123 blows away those magnetc particles 121 not restrained by the magnetc attraction from image 118, thus leaving on sheet 120 a configuration of magnetic particles which differentiates conductive from non-conductve areas. Hence by using theinvention herein, no

v transfer step is employed in making a difierentiating imv complishing the same* result.

ing passedtogether thereunder.

print upon sheet 120, and backgroundng is eliminated completely. In addition, no particles have contacted the face of plate 112 so as to scar it. V

FIGS. 7 and 8 illustrate an alternative method for ac- Plate 1 12, master and sheet are subjected to the field of magnet 117 by be- Then, without removing the master, particles 121 are spread upon sheet 120 and removed therefrom as was done above leaving a differentiating configuration thereon.

Printed circuits may be prepared in several ways utilizing the features described above. One method, a s shown in FIGS. 9 through 17, consists of marking a master 115 3,12o,eoe

upon a lamina 102 (FIG. 9) wherein a master 115 is prepared by a rubber stamp 130 using magnetic ink. However, it is to be understood that the process is not limited to this means and that any type of master 115, such as those shown in FIGS. 1 through 4, can be substituted with satisfactory results. The image plate 112 is positioned against master 115 and these two element-s pass together under the horizontal magnet 117 (FIG. 10). The master 115 is then removed leaving image 118 in the plate 112 (FIG. 11). The phantom stack 131 of sheets 120 (FIG. 10) indicates the alternative procedure illustrated in FIGS. 7 and 8, Wherein a sheet 12@ is placed on a master 115 prior to its passage under a magnet 117.

A sheet 120 is placed upon plate 112 and these members pass under hopper 122 so that it dispenscs partcles `'1 15 under distributive control of an air jet !123 (FIGS. 12 and 13).

'Referring to FIG. 29, the particles in the process just described are an aggregate of a finely divided (30 mesh or smaller is preferred, although larger particles are operable) ferromagnetc granule 140, such as soft iron, a similarly divided conductive granule 141, such as copper, and a finely divided granule of a fusing element 142, such as a granule `of solder or rose metal, for fusing all of these -aggregated particles 145 together into an electrcally continuous configuration. To aid fiusing element 4142, a finely divided grain of flux 143 is also present in particle 145. Finally, these granules are held together to form particles 145 by a s o-called core binder 144, such as waX or shellac or any of many well-known products which can be selected for this purpose. The aggregated particles thus described will be known as conductive magnetic" particles '145, since it is conductive granule 141 therein which will ultimately carry the current in the final product. The proportions of the Component granules may be arranged in accordance with the desred printed circuit characteristics.

The retentive force of image 113 (FIGS. 11 and 12) from beneath sheet `120 restrains the particles thereon against the removal force of the air jet 123 thereby leaving a deposit of magnetic particles upon the sheet 120 in the con figuration of representation 116. The "conductive magnetic particles :145, having been th-us formed into a circuit design or pattern 132 in accordance With representation 116 on master 1 15, will now appear in relief on sheet 1211 in the manner shown in the secti-onal View of FIG. 14. Plate 1:12 is removed after the particles have been fligned. To facilitate handling of sheet 12@ while particles 145 -are loosely aligned thereon subsequent to -removal of plate 112, it may be desirable, prior to removal of plate 112, to provide a moderate fusing of core binder 144 by means of a heat source, such as an inrared lamp.

In this condition, sheet 120 is next passed through an oven 133, shown diagrammatically in FIG. 15 as an openended enclosure 134 with a conveyor 135 and heating element 136. The temperature within the oven is selected such that element 142 will be fused and core binder 144 vaporized without damaging sheet 120. This result can be easily achieved through the proper selection of core binder 144, element 142, and sheet 1211.

The oven 133 causes the solder and fiux to bond the copper and ferromagnetic granules into a continuous electrical conductor; vaporizes the flux; and causes the core binder to attach to the sheet 121! the copper and ferromagnetic granules thus bonded. After sheet 12@ leaves oven 133, the fused circuit 146 thereon may be s-older dipped, as indicated in FIGS. 16 and 16a, to build up its electrical characteristics. Such dipping provides a coating 147 of solder upon circuit 146 to produce the electrically continuous printed circut .148 of FIG. 17.

A method, as shown in FIGS. 18 through 28, of preparing printed circuits by ctchin g consists of marking a master 115 by a rubber stamp 136 (FIG. 18) with magnetic ink 104. The process is not limited to this particular type of master, however, since any master 115, such as those shown in FIGS. 1 through 4 can be substituted With Satisfactory results. An image plate 112 of highly retentive magnetic material '113 is positioned against a mater 115, :and these two elements are subjected together to the fluX of a horizontal magnet 1-17 (see FIG. 19). 'Ihereaften master 1 15 is removed leaving image 118 in plate 112 (FG. 20). The phantom stack 131 of sheets in FIG. 19 indicates the alternative procedure illustrated in FIGS. 7 and 8, as explained above.

A sheet 12@ is placed upon plate 112 (FIG. 21) and passed therewith under hopper 122 so that particles 150 under distributive control of an air jet 123 (F-IGS. 21 and 22) are deposited upon sheet 1211. Because the instant process requires etching, rather than fusing as in the preceding process, in this instance the magnetic particles comprise a finely divided (300 mesh or finer preferred) ferromagnctic granule 1.40, such as soft iron, coated With a solubie etch-resistant material 151, such as wax or sheliac (see FiG. 30). Particles `1511 are distributed upon sheet 12@ (FG'S. 21 and 22) in the same manner as in the foregoing process. Thereafter particles 150 are fused (FIG. 23) by a heat source shown as an infrared lamp 15 3. Sheet 12@ in this process -is provided with a coating or layer of conductive material 154, such as copper (FIG. 24).

Having thus provided the desired protective coverng upon the conductive material 154 on the sheet `120', the letter is next subjected to an etching bath 155 shown schematically in FIG. 25. This etching bath removes all the conductive material 1541 not protected by the etchresistant material 151 and produces a product as shown in FG. 26. Finally, the etch-resistant layer is removed by immersing it in a solvent (FIG. 27), thereby producing a completed, printed circuit 154 upon an insulating sheet, as shown in FIG. 28.

In addition to producing printed electrical circuits, this invention can be used to produce or reproduce conventional printing by using fineiy divided pigmented magnetic particics 160, which may comprise an aggregate (-FIG. 31) of a finely divided (300 mesh or finer is preferred) ferromagnetic gran-ule 140, a similar ly divided pigment granule 161, such as graphite, and a core binder" 162 which can be easily fused, such as waX. The printer 2111, shown in FIG. 32, is used for producing original documents and the duplicator 301 of FIG. 36 for reproducing copy. The printer 2111 comprises a cylindrical image roller 212 having an outer surface of highly retentive magnetic material, such as cobalt-nickel. One end of roller 212 contains gear teeth 215 for engaging a reduction gear 248. Roller 212 is provided with an axis 216 for rotational mounting of the roller in suitable bearings (not shown).

Rotatably mounted around a fixed hollow shaft 2112 parallel with axis 216 of roller 212 is a character drum or cyiinder 253. This drum is mounted in suitable bearings 2114 and 2115 about shaft 262. A retainer ring 2116 is threadedly engaged toa hearing 'housing 2117 for retention of hearing 2134-. Bearing 235 is arranged within an internally protruding housing 214.

A photcmultiplier tube 2113 is mounted 'opposite one end of drum 2133 radially thereof and in registration with a path of elongatxed apertures 210 in drum 2113. Inside drum 2113 is a light source 211 is Secured to shaft 252, light source 21 1, photonultiplier 2118 and apertures 213 as they pass therebetween being alignment so as to produce alternating conditions of light and dark on photomultiplier tube 258. Rows of characters are located longitudinally upon drum 2113. A separate row is provided for each difierent character on the drum, and associated With each row of characters is one of the apertures 2111.

The construction of the face of drum 203 is best shown by referring to FIG. 33 which represents an enlarged portion thereof. Drum 233 is made of plastic With charactc rs 2119 of magnetic material having low retentivity &reason and high permeability embedded therein. For best results, a mu in excess of is desirable. In order to prevent the centrifugal expulsion of characters 2419 from drum 22 3 as it rotates, there is provided in each metal character a periphe ral slot or keyway 220 which receives a portion of the plastic drum material.

Referring now to FlG. 34, an alternative construction of drum 293 is shown comprising a magnetic material of high permeability and low retentivity with character depressions etched therein, as was shown and described above with regard to FIG. 3b. A non-magnetic supporting material 16@ (FIGS. 3b and 36) can be used to strengthen the drum if desired. 'In this embodiment, it is preferable to fill these depressions with plastic so that they do not collect dirt and [foreign particles. Etching will ordinarily cause a slight undercutting, as at point 217 (FIG. 3b). This slight undercutting prevents the centrifugal expulsion of plastic fillings 219 and is therefore desirable.

A single line of core-type vertical electromagnets 221 is axially aligned inside drum 203 (see FIGS. 32 and one magnet being provided for each colunn 222 of characters 209 on the drum. The field of each of these magnets covers an area thereunder one row high and a character wide. These magnets are fixed with relation to shaft 202 and are operated by means of electrical connections 223 leading from magnets 221 into and through the hollow interior of shaft '282 by way of ports 224 therein to an electrical pulsing source (not shown), such as the output of a data processing machine. The longitudinal axis of each magnet 221 is located along a radius of drum 203 approximately perpendicular to roller 212, the outer end or each magnet being located very close to the inner circumference of drum 203.

The mechanism for driving drum 2113` is comprised of t a drive gear 225 connected by a shaft 226 to a motor (not shown). Gear 225 drives a gear 227 mounted on a shaft 228 which protrudes from drum 2%. A pawl 230' is carried by the end face of drum 203 for driving a Geneva gear '231 so that for each revolution -of drum 23 3 Geneva gear 231 will rotate its associated shaft 232 one-Seventh of a revolution. Shaft 228 is provided with an arcuate dwell member 233 partially encircling shaft 228 with its open arcuate portion 234 radially opposite pawl 230, arranged to coact with the arcs 236 of Geneva gear 231. Roller 212 is intermittently driven in line spacing increments by gears 233 and 248, the latter being a reduction gear which drives the teeth 215 of roller 212.

A web 240' of paper upon which the ultimate printing of information is to be effected is fed to roller 212. Web 240 is then fed via sprocket gear 242a fixed to shaft '244 which is driven from teeth 215 of roller 212 via gears 241, 243 and 242 so that the linear speed of web 240 equals the peripheral speed of roller 212. A guide roller 245 is used to properly lead web 2 th` into roller 212.

An atomizer 250` is provided to deposit particles 160 upon web 240* as it is fed into roller 212. Thereafter, as the web is fed, a vacuum trap 254 is provided to remove eXcess particles before the web advances to a fixing station 251, which consists of several infrared lamps. A fixed magnet 255 is placed along the lateral surface of roller 212 for erasing the magnetic images 2 18 after each printing operation is fixed, and a suitable take-up roll 257 is positioned to receive the printed paper web 24@ as it leaves a paper feed sprocket roller 256- (FIG. 35).

In its operation, the printer 2411 follows the steps of a printing process which may be outlined as follows:

(l) A uniform magnetic field is created in an image i plate having an outer surface of highly retentive magnetic material (cobalt-nickel) backed up by a magnetic material of high permeability and low retentivity (image roller 212) by subjecting the highiy retentive surface to the field of a magnet (magnet 255).

(2) A master (drum 263) is positioned between a vertical electromagnet (magnet 221) and the image plate (roller 212 with its cobalt-nickel surface).

(3) The master and image plate are subjected together to the field of the magnet (by pulsing magnet 221).

'(4) Having thus prepared the image plate, a copy layer (paper 2 th) positicned thereon is sprayed with pigmented magnetic particles 16%, the excess thcreof being removed by the vacuum trap 254.

(5) The remaining deposit of pigmented magnetc particles is then heat fused.

Since the aforementioned Geneva mechanism and its associated gearing is arranged so that one-Seventh of a revolution of Geneva gear 231 provides a peripheral advance of roller 212 a distance of one line space, the surface of image roller 212 will be advanced one line spacing increment once during each revolution of drum 203. Member 233 seats itself in the arc 236 following the slot engaged by pawl 239, and thereby prevents roller 212 from turning when pawl 23@ is not actually engaged.

C'eating an image 218 upon the surface of roller 212 is accomplshed by pulsing a magnet when a selected character in the magnefis associated column '222 is directly beneath it. This is done as follows.

A photomultiplier tube 208, light source 211, and apertures 21@ passing therebetween cooperate to produce clock pulses which are suitably ampli-fied and fed to an electronic counter which dentifies the row of characters which is beneath the line of magnets 221 at any given time. The output from a storage means of a data processing machine selects the magnets (hence the columnar positions) to be pulsed for each row of characters. The coincidence of these two directives (indication of which row is in the pulsing position and indication of which magnets are to be pulsed at that time) is determined by a comparator associated with each magnet, and upon coincidence of the directives it acts upon its magnet via a multivibrator circuit causing the magnet to be pulsed. By this means, a line of magnetic images 218 of the characters on the character drum 2113 is created upon the image roller 212 for every revolution of the character drum 203. Since drum 293 moves a very small distance during the time that each magnet is pulsed, it is to be understood that the shape of the characters on the character drum is designed to compensate for this motion during pulsing.

Having thus prepared the image roller with a row of magnetic character images, the paper is fed over guide roller 245 and roller 212 past an atomizer 256` and vacuum trap 254 to fixing station 251, where particles are fused on the paper 240 'the paper then continues over the feed roller 256 to a take-up roll 2 57, and the operation cycle is completed (it is to be noted that images 218 on roll1er)212 are erased by magnet 255 after each operation cyc e Another embodiment of this invention may be in the form of a duplicating machine 3611, as in FIG. 36 which comprises a cylinder 196 rotatably actuated by any suit-v able means (not shown). Fastened to this cylinder is a master 1 -15 prepared, for example, in the manner suggested inFlG. 2 with magnetic ink 10 4 or magnetic carbon paper. `Inside cylinder 1% and opposite a layer 181 of highly retentive magnetic material upon a roller is located an image-creating horizontal magnet 197, which may be either of a permanent type (as shown) or electrically operated. It is to be understood from the earlier detailed explanation that magnet 197 can be a vertical magnet, and in this event a highly permeable magnetic hacking material having low retentivit such as roller 1%, is desirable as well as a magnet similar to magnet 255 of printer 2tl1 to provide an initially homogeneous ma gnetic field.

The balance of the apparatus of this duplicator is comprised of the same, or similar, elements as shown in printer 201 in FIG. 32, i.e. a roller 13@` with a surface of 3,12o,eoe

9 highly retentive magnetic material, atornizer 250, vacuum trap 254, and fixing station 251.

In its operation, this duplication machine performs as follows. The master 115 is first suitably fastened to cylinder 196. This cylinder is then rotated, thereby causing master 115 to pass beneath magnet 197. At the same time, roller 180 is rotated therewith by a suitable gearing mechanism (not shown), the Contacting surfaces of master 115 and roller 180' moving at the same speed. 'This produces upon layer 181 a magnetic image 218 of the printing on master 115.

A paper web 248' is fed over guide roller 245 and onto layer 181, past atomizer 25@ and vacuum trap 254 to heat fusing station 251. From this station, the web passes over roller 256 and proceeds to take up roll 257 (not shown).

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to the preferred ernbodiment, it Will be understood that various omissons and substitutions and changes in the form and details of the -device illustrated and in its operation may be made by those skilled in the art, Without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. The process of preparing a magnetic image member from which a printed pas ern may be magnetically reproduced including the steps of printing a permeabilitydiscontinuity type magneti-c pattenn representative of said printed pattern upon 'a first sheet, creating a homogeneous magnetic ux in a second sheet of magnetic material, placing said first sheet in surface contact with said second sheet, subjecting said `sheets non-selectively to a unidirectional magnetic fluX in a cross-sectional direction, and removing said first sheet thereby providing a magnetic image o f said pattern in said second sheet.

2. The process of prep aring -a magnetic image member comphising the steps of printing upon a sheet With a -marking material having a permeability sufficiently different from that of said sheet so as to vary the reluctance of said print ng With respect to the reluctance of said sheet, subjecting a sheet of highly retentive magnetc material to a source of unidirectional flux, plaoing the first said sheet upon the second said sheet, Wiping a permanent l@ magnet over the surface of the first said sheet, and removing the first said .sheet.

3. The process of preparng prin ted copy including the steps of forming a permeable magnetie pattern upon a first member, -plaoing said member in -ntimate relationslrip With a second member of magnetc material, providing a uniform magnetie fiux in said second member, subjecting said members to a unidireotional magnetic flux, removing said first member, pl acing a :sheet of non-magnetic matterial upon said second member, selectively distributing fusible magnetic particles pigmented With a mar-king material upon said sheet, and fusing said particles so dis tributed to form a printed copy of said pattern.

4. The process of preparing a magnetic image member for reproduoing a pn'nted pattern magnetically therefrom including the steps of pi-acin g a sheet having a magnetic pattern printed thereupon in the form of pemneability-discontinuities representative of said printed pattern in contact 'With a second sheet of magnetic material, subjecting such sheets non-selectively to a unidirectonal flux in the cross-sectional direction and removing said first sheet, thereby providing a magnetic image of said pattern in said second sheet.

References Citetl in the file of this patent UNITED STATES PATENTS 2,381,463 Potter Aug. 7, 1945 2,451,725 Franklin Oct. 19, 1948 2,473,729 Salz June 21, 1949 2,51l,l21 Murphy June 13, 1950 2,560,474 Potts July 10, 1951 Q,561,476 Lang July 24, 1951 2716368 Btei gerw' alt Aug. 30, 1955 2,718,849 Dresser Sept. 27, 1955 2,734,629 Mueller May l, 1956 2,735,784 Grei g et al. Feb. 21, 1956 2,743,629 Pellegrino u May 1, 1956 2,758,9*39 Sugarm an Aug. 14, 1956 2,802049 Masterson Aug. 6, 1957 2,848,748 Crump Aug. 26, 1958 -2,910,351 *Szlpak et al. Oct. 27, 1959 2,996,575 Sims Aug. 15, 196 1 FOREIGN PATENTS 733,484 Great Britain July 13, 1955 

3. THE PROCESS OF PREPARING PRINTED COPY INCLUDING THE STEPS OF FORMING A PERMEABLE MAGNETIC PATTERN UPON A FIRST MEMBER, PLACING SAID MEMBER IN INTIMATE RELATIONSHIP WITH A SECOND MEMBER OF MAGNETIC MATERIAL, PROVIDING A UNIFORM MAGNETIC FLUX IN SAID SECOND MEMBER, SUBJECTING SAID MEMBERS TO A UNIDIRECTIONAL MAGNETIC FLUX, REMOVING SAID FIRST MEMBER, PLACING A SHEET OF NON-MAGNETIC MATERIAL UPON SAID SECOND MEMBER, SELECTIVELY DISTRIBUTING FUSIBLE MAGNETIC PARTICLES PIGMENTED WITH A MARKING MATERIAL UPON SAID SHEET, AND FUSING SAID PARTICLES SO DISTRIBUTED TO FORM A PRINTED COPY OF SAID PATTERN. 